Field of the Invention
The present invention relates to a method and an apparatus for processing carbon nanotubes.
Description of Background Art
Carbon nanotubes have excellent electric conductivity (low electric resistance), excellent heat conductivity (high heat radiation), and high electric current density tolerance (high electromigration tolerance). For this reason, there is expectation that carbon nanotubes become a next generation wiring material for semiconductor devices and replace copper wire widely used in the art at this time. In order to use carbon nanotubes as wiring material, carbon nanotubes have a certain length, and multiple carbon nanotubes are arranged in a certain orientation. Also, to use carbon nanotubes, for example, in an electron emission element and the like utilizing field electron emission, a bundle of carbon nanotubes having a certain length is arranged with high density. However, since individual carbon nanotubes grow to various lengths during the course of their growth, the carbon nanotubes are processed to have a length appropriate to their purpose.
As a method for processing carbon nanotubes, there are a chemical mechanical polishing (CMP) method and a focused ion beam (FIB) method. For example, when CMP is employed, since dropping or peeling of carbon nanotubes may occur if they are polished directly, the polishing is performed by solidifying a bundle of carbon nanotubes using a silica-based solidification material. In such a case, the solidification material may be mixed into gaps among oriented carbon nanotubes, causing problems such as an increase in electric resistance.
As a technique of processing carbon nanotubes using a dry process, for example, JP 2001-180920 A proposes a processing method that includes a process of irradiating ions onto carbon nanotubes and an oxidization process. In addition, JP 2003-159700 A proposes a method for irradiating an electron beam at an energy level of lower than 120 keV onto carbon nanotubes. The entire contents of these publications are incorporated herein by reference. The entire contents of this publication (these publications) are incorporated herein by reference.